A solid cube of mass 5 kg is placed on a rough horizontal surface, in xy- 
plane as shown. The friction coefficient between the surface and the 
cube is 0.4. An external force $\overrightarrow{F}$ = 6$\hat{i}$ + 8$\hat{j}$ + 20$\hat{k}$ ​ N is applied on the cube. 
(use g = 10 m/$s^2$) 
(A) The block starts slipping over the surface 
(B) The friction force on the cube by the surface is 10 N. 
(C) The friction force acts in xy-plane at angle 12$7°$ with the positive 
x-axis in clockwise direction. 
(D) The contact force exerted by the surface on the cube is 10$\sqrt{10}$N. ​